My 7's been buzzing like crazy for several weeks now. Initially I thought it was the strings having that fresh-string sort of buzz, but it's only been getting worse. It's my Douglas Scope 727, it's buzzing like crazy, no matter what I adjust. I've spent a week trying out different truss rod tensions for the neck, and different actions (waiting until the next day to make any more changes, so as to allow the neck to relax a little bit). But nothing kills the buzz. It's either really bad buzz or really really bad buzz. It's on every single fret, regardless of how I press them. Notes still ring out, but it's audible in that it hurts my tones and kills the sustain. It's currently strung up with an Ernie Ball 8-string set, .13 - .74 in drop F. What sucks is that I can't take it to any techs, because none of them know how to work with anything lower than drop C, let alone a 7-string in an 8-string tuning.

What kind of crappy techs do you have around you that get scared of anything with more than 6 strings?

For the fretwork, you can try a visual inspection of the frets to see if any of them appear to be out of the slots.

And since you have a floyd, it could be work making a quick shim (using something like a business card) to see if that manages to take care of it for some reason. I doubt it will, but if you've tried everything else, why not?

Check all the screws and nuts, from the tuners to the back plate to the output jack... EVERYTHING. Make sure there's nothing loose. I used to have "buzz" on one my guitars and tried everything action-wise like you did, but it turned out to be a loose screw on the back plate.